It took that many men to bring the controversy about screening for prostate cancer onto the agenda again. There had never been a unanimous agreement about sense and nonsense of screening for prostate cancer, although it feels like that there is nowadays a generally accepted “must check” approach.
The British Medical Journal, BMJ, has now published a meta-analysis (summary) of six trials, where non-symptomatic men were screened for prostate cancer. (A meta-analysis is a statistical method to give more support to a particular opinion, because a possible error reduces with increased numbers.)
The participants were observed between four to fifteen years and the conclusion is: “The existing evidence … does not support the routine use of screening …”
Screening certainly diagnoses more cases of prostate cancer, however, during the study periods the same amount of men in the screening and non-screening group died of it.
This looks like a further nail in the coffin of prostate cancer screening. However I would prefer to keep the ‘body on the ventilator,’ because equally the conclusion could be that the existing evidence does not support the abandonment of current practice.
The article cites that certain parts of the original studies where of moderate quality. Additionally, an unknown number of men in the non-screening group were screened independently from the studies and treated independently. Finally a follow-up period of four years is too short, a period of fifteen years may just about be sufficient, as prostate cancer often is slow growing.
Furthermore within the next two to three years, two important studies will be published. Therefore I can’t see any need to hastily abandon screening and destroy the fragile health consciousness of men.
Undoubtedly, better screening tools are needed, the PSA test is crude, subjecting many men to unnecessary investigations. Investigations also need to be improved. Taking more tissue samples during a prostate biopsy increases the likelihood of finding cancer, including more serious cancer.
Finally, the approach to screening needs to be constantly reviewed. Definite current evidence states that risk groups do benefit from screening, above 75’s don’t and a small but neat study, which was published in the same edition of the BMJ looked at selective screening: frozen blood samples from 20 years ago were analyzed and compared with the medical notes of those men.
According to this study a PSA result at the age of 60, which was below 1.0 (ng/ml) made it extremely unlikely to suffer from serious prostate cancer 20 years later. A result of above 2.0 made it 17 times more likely to develop metastatic cancer than below this threshold of 2.0. If this is confirmed, even with current means, a significant number of men only would need an once-in-a-lifetime screening test.
About one in six men will be diagnosed with prostate cancer during their lifetime, one in 34 will die of it. According to the American Cancer Society, survival rate for treated cancer after ten years is 91%, after 15 years 76%. In the mid-70’s, 10-year survival rate was well below 30%, but increases do not only mean improvement in treatment. The active searching for cancer means that is diagnosed before causing symptoms, thus adding years to the survival rates.
Risk factors generally are a family history of prostate cancer, age and African origin. Smoking, lack of vegetables in the diet, sedentary lifestyle, tall height and high calcium intake are inconsistently cited as risk factors.